It should be no problem to use galvanized pipe as it's not that easy to rust. You know, outdoor towngas pipes are mainly made of steel, ductile iron or polyethylene.
Also, the valve which connects to the gas bottle should possess a safety devices such that it will automatically lock in case of gas leakage.
You do need to be aware if your gas bottles are placed within the proximity of your unit, which means, if that area belongs to you. If not, even just right outside the external wall, Lands Department may come over and remove it.